The present invention relates to an oil leakage sensor element which detects leakage of oil onto a water surface by means of a change in electrical resistance.
A conventional oil leakage sensor element is an element in which two conductors are separated by a polytetrafluoroethylene (PTFE) film containing carbon particles. When oil leaks onto the surface of water in which this sensor element is installed, the oil permeates the areas between the carbon particles inside the resin, and lowers conductivity arising from the tunnel effect. This causes a change in the electrical resistance value of the sensor element, and the oil leakage is detected as a result of this change in electrical resistance.
In the case of the abovementioned conventional sensor element, the PTFE is unsatisfactory in terms of permeability to high-viscosity oils such as heavy oils, especially grade C heavy oils, and vegetable oils. Furthermore, most of the carbon particles are surrounded by PTFE. As a result, the leaking oil does not achieve sufficient contact with the carbon particles. Consequently, the change in the electrical resistance value of the sensor element at the time of oil leakage is small, so that the oil leakage detection sensitivity is unsatisfactory.
The present invention was designed in light of the abovementioned problems encountered in the prior art. The object of the present invention is to increase the change in the electrical resistance value of an oil leakage sensor element by improving the permeability of the element to high-viscosity heavy oils, and sufficiently increasing the contact of the oils with the carbon particles in the element.